1. Field of the Invention
The invention is generally related to semiconductor processing, and more particularly to methods of hydrogen conservation and recycling in semiconductor processing operations.
2. Related Art
There are numerous semiconductor reactors, which are designed to perform various semiconductor processes on semiconductor substrates. Typically, during many of these processes hydrogen gas is employed for various purposes. For example, a method is disclosed in U.S. Pat. No. 5,660,682, for removing undesired material from an integrated circuit. In this method, a flow of argon and hydrogen are energized in a reactor to form a plasma, which reacts with the material to be removed, to form a gaseous product. The gaseous product is then subsequently removed from the reactor. In another example, a method is disclosed in U.S. Pat. No. 5,882,424, for depositing a thin film of Ti or TiN on a substrate by plasma enhanced CVD, which uses H2 as a preferred process gas.
Although, these exemplary uses of hydrogen in semiconductor processes are by no means exhaustive, they do suggest the potential advantage of hydrogen use to the semiconductor processing art. Unfortunately, hydrogen tends to be wasted in large amounts from most processing systems. Moreover, the excess hydrogen poses a potential fire and explosion hazard. For this reason, the excess hydrogen is typically burned away in a relatively costly process. Moreover, since hydrogen is itself a relatively expensive gas, processing costs for process including hydrogen may be substantial. Hydrogen is also difficult to store in large amounts in vapor phase do to volume requirements. Thus, hydrogen is typically stored in liquid phase, and converted to vapor phase, requiring large amounts of energy.
For these reasons, what is needed is a system and method for conserving and/or recycling hydrogen used in semiconductor processing operations, which may reduce hazards, costs, and energy consumption.
The present invention provides a system and method for conserving and/or recycling hydrogen used in semiconductor processing operations. The present invention can be used with any conventional reactor, which supports semiconductor processes using hydrogen. Alternatively, the present invention can be used with a modified reactor, described in detail below.
In the present invention, hydrogen is pumped into the reactor from a hydrogen gas supply chamber. The hydrogen is used in the reactor as needed to perform the process function. The hydrogen accompanied with other process gases is exhausted from the reactor. The exhausted gases are routed through a scrubber, which is used to separate the hydrogen from the other gases. The other gases are allowed to vent from the system in a typical manner. The hydrogen is then pumped through an H2 purifier, which cleans the hydrogen gas making the gas once again useable in the semiconductor process.
In one aspect of the present invention, a process is provided for recycling a vapor-phase chemical. The method includes introducing vapor-phase chemicals into a reactor with sufficiently supplied energy to cause a reaction in said reactor; exhausting gases resulting from the reaction; separating a first gas from the exhausted gases; purifying the first gas; and thereafter introducing the first gas into the reactor.
In another aspect of the invention, a system is provided for recycling a vapor phase chemical. The system includes a reactor chamber capable of receiving and exhausting the vapor-phase chemicals. A gas scrubber is also provided, which is capable of receiving the vapor-phase chemicals exhausted from the reactor chamber. The scrubber outputs a first gas; which is directed to a gas purifier capable of purifying the first gas. Once the first gas is purified it is returnable to the reactor chamber.
Advantageously, the present invention may return between approximately 80% to 90% of the initial hydrogen let into the reactor. Accordingly, if for example, 90% of the hydrogen is returned to the reactor, only 10% of the initial amount needs to be added for subsequent processes. The conservation and recycling of hydrogen used in semiconductor processing operations helps to reduce processing costs. For example, since the hydrogen requirement is reduced, the need to convert large amounts of liquid hydrogen to gaseous hydrogen is removed, which lowers overall energy consumption.
These and other features and advantages of the present invention will be more readily apparent from the detailed description of the embodiments set forth below taken in conjunction with the accompanying drawings.